Investigation Summary
The investigation into Flight 2174 focused on the aerodynamic degradation caused by atmospheric icing. Meteorological analysis suggested that the aircraft likely accumulated approximately 15 millimeters of ice during its descent. This level of accretion on the leading edges of the wings and tail surfaces would have severely disrupted airflow, leading to a stall or uncontrollable pitch-down moment. A critical finding was the state of the cockpit switches: the anti-icing system was found in the 'off' position. While the crew recognized the performance loss and increased engine power, they failed to activate the thermal or mechanical de-icing equipment. The reason for this omission, whether due to a late recognition of the icing severity or a checklist error, could not be definitively established.
Final Conclusions
The crash was caused by the accumulation of ice on the aircraft's surfaces, which led to a loss of lift and control during the approach phase. A contributing factor was the failure of the crew to activate the aircraft's anti-icing system, despite operating in known icing conditions.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Anti-Icing System
A system designed to prevent or remove ice buildup on wings and tail surfaces; it was found deactivated.
Antonov An-24B Airframe
The high-wing turboprop design was susceptible to significant lift loss when leading edges were contaminated by ice.
Interesting Facts
- 01The aircraft had accumulated 10,913 flight hours and 8,544 cycles prior to the accident.
- 02Investigators estimated that 15 millimeters of ice had developed on the airframe.
- 03The wreckage was located 1,130 meters to the right of the runway centerline.
- 04All 57 people on board (53 passengers and 4 crew) were killed in the impact and subsequent fire.
- 05The anti-icing system switches were found in the off position in the wreckage.
Safety Actions & Advisories
Icing Awareness Training
The accident highlighted the critical need for early activation of anti-icing systems in Soviet turboprop operations during winter months.